General Biology:Ospreys are large raptors with a wingspan of five or more feet. They are dark brown above, white below, with a white head and a prominent dark eye stripe. They are easily identified while hovering in the air 30'-100' over a large body of open water. Their long narrow wings are always angled and bowed down, in the shape of the letter M.

Osprey on a roosting pole. Inset: an Osprey diving for food.

Fish and Wildlife Service

Behavior:

The Osprey is one of the most specialized hawks. It finds its prey by hovering high over open water, waiting for a fish to approach the surface. Ospreys plunge talons first completely submerging if necessary after the unsuspecting fish. Ospreys are often rated as the most powerful birds of prey based on a ratio comparing their body weight to the size of the prey they are capable of flying with. Ospreys are known to carry up to 40% of their body weight, and anecdotal evidence has reported weights up to 100%.

The Osprey is also equipped with special barbed pads on the soles of its feet to help grip the slippery fish. This adaptation comes in especially handy where territories overlap with Bald Eagles as the latter often tries to steal fish already caught by the Osprey.

Ospreys build their nests in a live or dead tree near or over water. The nest is constructed by both the male and female with sticks, sod, cow dung, seaweed, or whatever material is available. Once a pair has bonded, the female will be fed entirely by her mate while she sits on the eggs. This feeding may insure mate fidelity. After the eggs hatch, the male continues to be the primary provider for the family group, performing 70 percent of the hunting until the young have fledged.

Usually three eggs are laid and will hatch after 32-43 days. Ospreys are such good parents that siblicide is uncommon. Unlike eagles and other hawks, Osprey parents can usually supply their young with enough food that there is no need for the largest sibling to kill its brother and/or sisters to insure its own food supply.

Osprey Nesting Platform

US Fish and Wildlife Service

Conservation:
Like Bald Eagles, Ospreys were another bird species that was severely affected by DDT poisoning. This chemical was used in the U.S. extensively during the 1950s and 1960s as an insecticide. The poison was transferred from insect to fish, to fish-eating birds causing poor egg and embryo development. In some populations, hatching success was less than 20% (in developing countries DDT is still widely used to control malaria). Coastal populations in the United States have successfully recovered with the banning of DDT and conservation programs using artificial nesting platforms. Inland populations are still very low, however. We are very proud of the recent and natural return of Osprey to Bryce Canyon National Park.

Habitat range of the Osprey

US Fish and Wildlife Service

When and where to see at Bryce:
Osprey can be viewed nesting in Bryce Canyon from late May through July and making fishing trips to and from Tropic Reservoir. There are two nests along the park's scenic drive. Look for large stick nest at the top of dead trees. One nest is easily viewed in the vicinity of Farview Point, near mile marker 10. For the overall health of these birds, we ask that you do not approach the nest. Please be a responsible bird lover and view them with binoculars from the shoulder of the road.

Further Reading:
Dunn, John L. 1999. The National Geographic Field Guide to Birds: 3rd Edition. National Geographic, Washington D.C.

Erlich, Paul R. et al. 1988. The Birder's Handbook: a field guide to the natural history of North American Birds, Simon and Schuster/Fireside Books, New York

Ryser, Fred A. 1985. Birds of the Great Basin: A Natural History. University of Nevada Press

Sibley, David Allen. 2001. The Sibley Guide to Bird Life and Behavior. Knopf Publishing